What's already happened to open-plan offices is that they are at least half empty due to remote work. People go to them to interact with coworkers as much as for a quiet space. People go specifically to be available for face to face conversation, so loud conversations are heard.

Voice isn't my main input but the handful of times I voiced something in the middle of an office, I spoke quietly, with a near whisper, into a close mic. It was much quieter than I would normally be able to speak to a coworker.

tall, thick cubicle walls.

Along with noise cancelling headphones, noise canceling microphones will probably get really good.

There are microphones that can capture whispers and even subvocal dictation: https://youtu.be/NvVbCqDgfCs?t=520

The one demo'ed in the video is BOYA BY-GM18CU (https://www.amazon.com/dp/B0BF969RVP)

That one captures whispers. I've heard other devices can dictate based on vibrations from your neck/chest.

I've adopted voice as my main input, and i love it, It is much faster than text. and for your question, i do think NC headphones will become the default for open floor plan offices, or maybe microphones than captures whispers.